One is a millionaire author who has become Britain’s wealthiest self-made woman, the other works as an office clerk. Yet the bond between the Harry Potter author, JK Rowling and her close friend Fiona Wilson, forged when they were both single mothers living in Edinburgh, is clearly a very strong one. The Scots-based writer has become the latest celebrity to use her wealth to reward loyalty by giving Fiona a £150,000 flat in one of Edinburgh’s most desirable areas.